TESARO Announces Presentation of Niraparib Clinical Data at the 2013 ASCO Annual Meeting

TESARO Announces Presentation of Niraparib Clinical Data at the 2013 ASCO
Annual Meeting

  *Final Phase 1 Results Demonstrate Activity in Ovarian and Breast Cancer
  *Phase 3 Trial in Ovarian Cancer to Begin Enrolling Patients by Mid-Year
  *Phase 3 Trial in Patients With Breast Cancer on Track to Initiate in 2H13

WALTHAM, Mass., May 16, 2013 (GLOBE NEWSWIRE) -- TESARO, Inc. (Nasdaq:TSRO),
an oncology-focused biopharmaceutical company, today announced that final
results from a Phase 1 trial of niraparib, an inhibitor of poly ADP-ribose
polymerase (PARP), will be presented at the American Society of Clinical
Oncology (ASCO) annual meeting in Chicago. These results include anti-tumor
activity and safety data for 100 patients with solid tumors, including 49
patients with high grade serous ovarian cancer (HGSOC) and twelve patients
with breast cancer. Full, updated results relating to the abstract will be
provided during the investigators' poster presentation on June 4, 2013.

"We are pleased that these data confirm the preliminary results presented at
ASCO in 2011, and support advancement of niraparib into Phase 3 trials,"
stated Dr. Mary Lynne Hedley, President of TESARO. "We remain on track to
begin enrolling patients in a Phase 3 trial in the ovarian cancer maintenance
setting by mid-year, and to initiate a Phase 3 trial in patients with breast
cancer during the second half of 2013."

Investor Briefing

TESARO will host an investor briefing in Chicago on Sunday, June 2 at 6:15 PM
local time in conjunction with the ASCO annual meeting. At this briefing,
TESARO management will review niraparib clinical data, discuss development
plans in ovarian and breast cancer and answer questions from analysts and
investors. This event will be webcast live and archived for 30 days at

ASCO Data Presentation Details

Final Results of the Phase I Trial of Niraparib (MK4827), a Poly(ADP)ribose
Polymerase (PARP) Inhibitor Incorporating Proof of Concept Biomarker Studies
and Expansion Cohorts Involving BRCA1/2 Mutation Carriers, Sporadic Ovarian
and Castration Resistant Prostate Cancer (CRPC), Poster #2513, June 4, 2013
from 8:00 AM to 12:00 PM; 11:30 AM discussion


TESARO is an oncology-focused biopharmaceutical company dedicated to improving
the lives of cancer patients by acquiring, developing and commercializing
safer and more effective therapeutics. For more information, visit

To the extent that statements contained in this press release are not
descriptions of historical facts regarding TESARO, they are forward-looking
statements reflecting the current beliefs and expectations of management made
pursuant to the safe harbor provisions of the Private Securities Litigation
Reform Act of 1995. Words such as "may," "will," "expect," "anticipate,"
"estimate," "intend," and similar expressions (as well as other words or
expressions referencing future events, conditions or circumstances) are
intended to identify forward-looking statements. Forward-looking statements
involve substantial risks and uncertainties that could cause our clinical
development programs, future results, performance or achievements to differ
significantly from those expressed or implied by the forward-looking
statements. Such risks and uncertainties include, among others, the
uncertainties inherent in the initiation of future clinical trials,
availability of data from ongoing clinical trials, expectations for regulatory
approvals, and other matters that could affect the availability or commercial
potential of our drug candidates. TESARO undertakes no obligation to update or
revise any forward-looking statements. For a further description of the risks
and uncertainties that could cause actual results to differ from those
expressed in these forward-looking statements, as well as risks relating to
the business of the Company in general, see TESARO's Form 10-K for the year
ended December 31, 2012.

CONTACT: Investor/Media Contact:
         Jennifer Davis
         Sr. Director, Corporate Development & Investor Relations
         +1.781.325.1116 or jdavis@tesarobio.com

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